Exfoliation syndrome and exfoliation glaucoma

Exfoliation syndrome-abnormal deposition in the anterior segment of the eye of an unknown substance thought to be related to elastic fibres and baseme nt membrane components-is associated with accelerated cataract progression, increased frequency of intraoperative and postoperative complications and increased risk for glaucoma and, therefore, is a clinically important findi ng. A clear association has been shown with age. The syndrome occurs worldw ide but its prevalence seems to vary from country to country. The best-know n sign of exfoliation syndrome is deposits of greyish-white material on the anterior lens surface. Sometimes exfoliation material can also be seen at the pupillary border, on the anterior iris surface, corneal endothelium, an d on the anterior vitreous face. When clinically detected, exfoliation synd rome is somewhat more often unilateral than bilateral. According to recent investigations clinically unilateral exfoliation syndrome is probably never truly unilateral but rather asymmetric, because exfoliation material has b een detected ultrastructurally and immunohistochemically around iris blood vessels of the nonexfoliative fellow eyes. Indeed, electron microscopy iden tifies in various organs of patients with exfoliation syndrome fibrils simi lar to those seen in intraocular exfoliation deposits. Other clinical signs associated with exfoliation syndrome are pigment dispersion, transillumina tion defects of the iris and reduced response to mydriatics. In unilateral exfoliation syndrome, intraocular pressure (IOP) of the exfoliative eye is approximately 2 mmHg higher than IOP of the nonexfoliative fellow eye. Whet her elevated IOP, vascular changes or exfoliation syndrome itself is the ma in Factor causing optic serve head damage and conversion of an exfoliative eye to glaucomatous, is not known. Glaucoma in the exfoliation syndrome has been shown to have a more serious clinical course than in primary open-ang le glaucoma (POAG). Al the rime of diagnosis, IOP and its diurnal variation are generally higher and visual field defects tend to be greater in exfoli ation glaucoma than in POAG. Because the decrease in IOP variation and lowe ring of the mean IOP level has been shown to improve visual field prognosis more in exfoliation glaucoma than in POAG, the glaucomatous process is con sidered to be more pressure-related in exfoliation glaucoma. Furthermore, p rogression of optic disc damage has been shown to be similar in exfoliation glaucoma and POAG when IOPs are lowered to a comparable level by the treat ment. However, vascular disturbances in the posterior segment of the eye mi ght after all be of equal importance in these two types of glaucoma; optic disc hemorrhages and venous occlusions have been reported to be as frequent in exfoliation glaucoma as in POAG. Perhaps in exfoliation glaucoma circul atory disturbances combined with high IOP lead to a particularly relentless ly progressing form of the disease. (C) 2000 Elsevier Science Ltd. All righ ts reserved.